Atypical antipsychotic agents are widely used for a range of psychiatric disorders in the elderly. However, elderly patients are more susceptible to antipsychotic side effects than adults due to their age-related changes in drug disposition and response. Studies have suggested that elderly are at-risk for cerebrovascular events, metabolic alterations, falls, and movement disorders due to atypical agents. The recent clinical trials revealed that adverse effects limit the usefulness of atypical agents for psychosis, aggression, and agitation in the elderly. These safety and efficacy profiles will have diverse health care consequences in the elderly. However, little is known about health care utilization in elderly patients using antipsychotic agents. This study extends the investigators'prior work to evaluate the heath care impact of antipsychotic use in the elderly. Specific aims of the study are: (1) to describe the use of atypical antipsychotic agents in the elderly;(2) to examine the overall health care use among the elderly using typical and atypical agents;and (3) to compare the overall health care use among the elderly using olanzapine, risperidone, and quetiapine. Using a retrospective cohort design involving elderly Medicare and Medicaid (dual eligible) patients 65 years or older, the proposed study will test the hypotheses that: (i) the overall health care use will be higher among the elderly using atypical agents when compared to those using typical agents;and (ii) the overall health care use differs across atypical antipsychotic agents. Health care use will be evaluated using measures such as hospitalization, outpatient visits, emergency visits, and prescription utilization. The 2001-2003 Medicare and Medicaid claims data from four states with high numbers of dual eligible beneficiaries will be used. The Heckman selection method will be used to adjust for the selection bias within the multivariate context of the Andersen Behavioral Model to examine the health care use associated with atypical agents in the elderly. This investigation will provide valuable information to health care providers and policy makers by addressing the cumulative health care impact of atypical agents due to their safety and efficacy profiles. In addition, the findings will be beneficial in optimizing atypical antipsychotic use and expenditures in the elderly. PUBLIC HEALTH RELEVANCE: With increasing evidence of efficacy and safety concerns of atypical agents, there is a need to evaluate atypical antipsychotic use in the elderly. Little is known about the cumulative health care impact of atypical agents due to their safety and efficacy profiles. An evaluation of health care utilization in the elderly will be valuable to health care providers and policy makers to optimize the use and expenditures of atypical antipsychotic agents in this vulnerable population.